Does nationalism produce resistance to foreign military occupation? The existing literature suggests that it does. Nationalism, however, also can lead to acquiescence and even to active collaboration with foreign conquerors. Nationalism can produce a variety of responses to occupation because political leaders connect nationalist motivations to other political goals. A detailed case study of the German occupation of France during World War II demonstrates these claims. In this highly nationalistic setting, Vichy France entered into collaboration with Germany despite opportunities to continue fighting in 1940 or defect from the German orbit later. Collaboration with Germany was widely supported by French elites and passively accommodated by the mass of nationalistic French citizens. Because both resisters and collaborators were French nationalists, nationalism cannot explain why collaboration was the dominant French response or why a relatively small number of French citizens resisted. Variation in who resisted and when resistance occurred can be explained by the international context and domestic political competition. Expecting a German victory in the war, French right-wing nationalists chose collaboration with the Nazis as a means to suppress and persecute their political opponents, the French Left. In doing so, they fostered resistance. This case suggests the need for a broader reexamination of the role of nationalism in explaining reactions to foreign intervention.

When do states acquire nuclear weapons? To address this question, a strategic theory of nuclear proliferation must take into account the security goals of all of the key actors: the potential proliferator, its adversaries, and, when present, its allies. To acquire nuclear weapons, a state must possess both the willingness and the opportunity to proliferate. Willingness requires the presence of a grave security threat against which no ally offers reliable protection. Opportunity requires that the state pursuing nuclear weapons possess high relative power vis-à-vis its adversaries or enjoy the protection of a powerful ally. Whereas a relatively weak state without a powerful ally lacks the opportunity to develop a nuclear capability, one with such an ally lacks the willingness to do so. Therefore, only powerful states or relatively weak states with allies that do not guarantee fulfillment of at least some of their key security goals will acquire the bomb. These claims are supported by the overall pattern of nuclear proliferation as well as detailed analyses of the Soviet, Iraqi, Pakistani, South Korean, and West German nuclear development cases.

The United States has been at war for thirteen of the twenty-two years since the Cold War ended and the world became unipolar. Still, the consensual view among international relations theorists is that unipolarity is peaceful. They base this view on two assumptions: first, the unipole will guarantee the global status quo and, second, no state will balance against it. Both assumptions are problematic. First, the unipole may disengage from a particular region, thus removing constraints on regional conflicts. Second, if the unipole remains engaged in the world, those minor powers that decide not to accommodate it will be unable to find a great power sponsor. Placed in this situation of extreme self-help, they will try to revise the status quo in their favor, a dynamic that is likely to trigger conflict with the unipole. Therefore, neither the structure of a unipolar world nor U.S. strategic choices clearly benefit the overall prospects for peace. For the world as a whole, unipolarity makes conflict likely. For the unipole, it presents a difficult choice between disengagement and frequent conflict. In neither case will the unipole be able to easily convert its power into favorable outcomes peacefully.